Multi-layer coatings of the color- and/or special effect-imparting base coat/outer protective and gloss-imparting clear top coat type are state of the art in the field of automotive coating, which includes automotive refinish coating as well as automotive OEM (original equipment manufacturer) coating of vehicles and vehicle parts. It is also state of the art to apply the base coat layer of said multi-layer coatings from environmentally-friendly waterborne base coat compositions.
There is still a need for the development of waterborne base coat compositions with improved stability. This is particularly true with regard to aqueous effect base coat compositions, especially aqueous metallic base coat compositions. Waterborne base coat compositions with a tendency towards instability often exhibit an undesired color shift over time, especially in case of aqueous OEM base coat compositions which are typically conveyed in circulating lines.